I was recently reading Eric Frank Russell's Great World Mysteries when I came across one of the most horrific sea-monster reports. I had read of it before somewhere, but here was a chance to refresh my memory.
A diver in the South Pacific was somewhat alarmed to find a shark in his vicinity. He lowered himself in the water, until the shark was about twenty feet higher than he. The diver then came across a huge chasm of unguessed depth. Up from this chasm there rose a great creature, colored brown and about an acre in extent. It doesn't seem to have had discernable features such as eyes. It was, however, pulsating. It rose ever higher until it reached the level of the shark and absorbed the fish, which seemed paralysed, into its body.
In the slow and deliberate fashion in which the monster had risen, it sank back once more inot the chasm below.
This incident was reported in 1953.